change up and moreover actionbar icon style

in values/styles.xml:

Adding % in strings.xml

just add formatted="false" in the entry:

Please the field %s, in %s, should have a value!

Get connectivity in android

Common solution:

ConnectivityManager cm =
        (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
 
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting();

Using a broadcast receiver when the network state change:

Post data in body part

try {
  URL url = new URL("http://requestb.in/14a9s7m1");
     HttpURLConnection conn;
      conn = (HttpURLConnection) url.openConnection();
     conn.setRequestMethod("POST");
     
      conn.setDoOutput(true);
     
  
     OutputStream os = null;
     try {
      os = conn.getOutputStream();
      os.write("fkdlsakl!".getBytes());
   } catch (Exception e) {
      e.printStackTrace();
     }   
     os.close();
     
     conn.connect();
      int respCode = conn.getResponseCode();
  
      if(respCode == 200) {
       InputStream ip = conn.getInputStream();
//       response.headers = conn.getHeaderFields();
       int s = ip.read();
       ip.close();
      }
  } catch (Exception e) {}